This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Nudaurelia capensis omega virus-like particle, a T=4 virus capsid, undergoes a pH promoted maturation process. Using the fully upgraded instrumentation on SSRL BL4-2 we have begun studying the kinetics of structural change associated with the maturation process. Performing manual mixing, followed by a series of time-resolved data acquisition (each 3 sec exposure), we have recently been able to isolate a structural intermediate at intermediary pH values between neutral (pH 7.6) and pH 5.0, which was used to promote the maturation in our earlier studies. We also observed that two VLPs with different RNA contents show slightly different shape and diameter. We have initiated the time-resolved studies of the entire process of maturation with a millisecond time-resolution in an attempt to examine our hypothesis that the repulsive electrostatic forces among the capsid subunits at the 3-fold and quasi 3-fold axies being the key triggering event in the maturation.